In free-standing easel-back frames or piano frames, or in passe-partout assemblies, the backing sheet and spacer and mat are separable elements that are held together in the former instance in a separable rigid frame and in the latter instance by strips of cloth or paper pasted over the edges. Such assemblies, of course, are relatively heavy and expensive and are often glazed and so are used in the manner of ordinary pictures.
The field of use of the present invention is quite different from that of those heavier individual mountings described immediately above. The present invention relates to that field of mounting in which it is desired to display one or a plurality of images, singly or in assembly, as thin, inexpensive sheets which can be assembled in albums or books in loose-leaf or permanently bound fashion, or as greeting cards and the like.
In these latter constructions, it would be highly desirable to be able to market the display frame as an assembled unit of backing sheet, spacer and mat, ready to receive the image inserted by the user. However, it is difficult to make such an assembly which will be both permanent and easy to use. The assembly should provide a definitive position for the image, from which the image cannot readily become displaced. Thus, in such an assembly, the image should be easy to insert and remove, but secure against accidental dislodgement or mispositioning.
A construction for this purpose has been proposed, in SAMES U.S. Pat. No. 2,253,814 of Aug. 26, 1941. In this construction, a slit is provided across the backing sheet, through which the image can be inserted to a position in which the image is bordered by the spacer and hence framed by the mat.
But this prior art construction has several disadvantages. In the first place, it is often desirable to make such display frames double sided, so that they can display a picture on opposite sides. Especially if the frames are assembled in an album or book, the thickness of the assembly can be substantially reduced if the frames are double sided. In the second place, the side of the display frame opposite the image is rendered unsightly by in effect being slashed across its width.